Radiometric dating of Svecokarelian metarhyolites and prekinematic granitoids from Bergslagen, south central Sweden

Geochemistry, age, and origin of the Högberget granite, western Bergslagen, Sweden

“…UPb dating of zircons from the felsic volcanics have yielded ages of 1.88-1.90 Ga (Åberg et al 1983;Welin 1987). The volcanic rocks are in time and space associated with Early Svecofennian intrusions ranging in composition from gabbros to granites (Wilson 1980;Gaál & Gorbatschev 1987) with ages in the interval 1.87-1.90 Ga (Åberg & Strömberg 1984;Åberg et al 1983;Wilson et al 1985;Welin 1990). All Early Svecofennian units were subject to regional metamorphism during the Svecofennian orogeny.…”

Radiometric dating of Precambrian rocks in Småland, southeastern Sweden

“…Subsequent disturbances after emplacement would have the effect of a partial homogenization of the R&Sr systems, which in turn would be mirrored in a rotation of the isochron towards lower ages and higher initial Sr ratios. In this case, the correlation will be less than if the sampling had been restricted to one locality as pointed out by Aberg 6r Stromberg (1984).…”

Tectonic implications of an 1846±1 Ma old migmatitic granite in south‐central Sweden

“…The 1846±1 Ma age also brackets the termination of Svecofennian subduction processes in south-central Sweden to an interval between 1846+1 and 18693Í Ma (granitoid at Ludvika, Åberg & Strömberg 1984). Furthermore, as crustal thickening requires the collision of large crustal fragments, not only arcs that would accrete without any additional crustal thickening, it is most likely that the generation of crustal melts in the Svecofennian region post-dates the extermination of the last subduction zone in the Svecofennian region and post-dates the collision of the Svecofennian terranes, which earlier had been assembled to one coherent mass consisting of several magmatic arcs, with the Archaean block (Romer & Smeds 1994).…”